1. Field of the Invention
The present invention relates to a method for packaging electronic parts and an adhesive for use in said method.
2. Description of the Related Art
When an electronic part such as a chip resistor or a chip capacitor is soldered on a printed board, it is temporarily mounted on the printed board with a photopolymerizable and thermopolymerizable adhesive comprising a polymerizable compound having different photopolymerizable functional group and thermopolymerizable functional group (cf. Japanese Patent Kokai Publication No. 63-72195). In such method, the adhesive is applied on a part of a board surface at which the electronic part is mounted and gelled through irradiation of light, whereby its viscosity is increased. Thereafter, the electronic part is pressed against the viscous adhesive to temporarily mount the part to the printed board and then soldered to the printed board. During soldering, the adhesive is thermally cured.
In the above packaging method, when the adhesive is applied to the printed board, its viscosity is kept low so that the adhesive can be easily applied with suitable means such as a dispenser, and when the electronic part is mounted, the viscosity of the adhesive is increased to decrease flowability of the adhesive and to impart pressure sensitive adhesion so as to prevent dislocation of the electronic part. Further, while soldering the electronic part to the printed board, the adhesive is thermally cured to impart heat resistance to the adhesive and to prevent dislocation of the electronic part. The adhesives to be used in the above packaging method are disclosed in Japanese Patent Kokai Publication No. 63-15948.
Although the above packaging method may achieve the intended effects to make mounting of electronic parts easy, it is still desired to improve the packaging method so as to further decrease packaging defects of the electronic parts. That is, improvement of flowability of an adhesive is still desired.